Urinary nitric oxide synthase activity and cyclic GMP levels are decreased with interstitial cystitis and increased with urinary tract infections.

Since urinary nitric oxide synthase (NOS) activity correlates with certain disease process affecting the urinary tract and since nitric oxide increases cyclic GMP levels by activating guanylyl cyclase, urinary particulate NOS activity and cyclic GMP levels are evaluated in female patients with interstitial cystitis (IC) and compared with those from female controls and female patients with urinary tract infections (UTIs). Urinary NOS activity is measured as the formation of [(14)C]-L-citrulline from [(14)C]-L-arginine, and urinary cyclic GMP levels are measured by an [(125)I]-radioimmunoassay. Female patients with IC have significantly less NOS activity in their urine pellet particulate fractions than female control females UTIs, 2.3 +/- 1.0, 14 +/- 3.0, and 120 +/- 10 pmol. citrulline formed/min./mg. protein. Urinary cyclic GMP levels are significantly lower in IC patients than in female controls or females with UTIs: 0.50 +/- 0.06, 0.82 +/- 0.14. and 3.72 +/- 0.81 micromol. cyclic GMP/g. creatinine. Regulation of urinary NOS activity with subsequent changes in nitric oxide and cyclic GMP may be an important determinant of symptoms and immunologic responses to UTIs and IC.